Although, refs. [1]}, [2]}, [3]} discuss design techniques and controls for increasing the passivity behavior of VSC with LCL filter and current control. The techniques and controls have to be carefully considered before adapting to GFC.
Similarly, ref [4]} also discusses the challenges and methods in ensuring passivity until the Nyquist frequency range (\(0-fs/2\) )for cascaded voltage-controlled converters. In conclusion to this section, it can be said that the requirement of GFC behaving as a voltage source behind an impedance in the frequency range of interest is satisfied for GFC without inner loops, whereas it is not straightforward for GFC's with inner loop to ensure passivity. Furthermore, as the converter is rated for high power, the switching frequency reduces, thus aggravating the stability issues due to the nonpassive behavior of power converter impedances.
